A low-dropout regulator (LDO) is a direct current (DC) linear voltage regulator that can regulate the output voltage even when the supply voltage is very close to the output voltage. As semiconductor technology advances, the designing of LDOs has become a critical aspect of the manufacturing process of three-dimensional (3D) NAND flash memories, in which the memory cells are stacked vertically in multiple layers to achieve higher densities at a lower cost per bit.
Conventional analog LDOs are widely used in a variety of circuit structures. In order to ensure the output stability of the LDOs under different load conditions, a high quiescent power and a large decoupling capacitance are important. Existing analog LDOs have a low bandwidth and a slow load transient response speed. On the other hand, existing digital LDOs also have drawbacks, such as higher noise, higher switching power, complex architecture, and complicated algorithm control.
Accordingly, the disclosed low-dropout regulators are directed to solve one or more problems set forth above, and other problems.